A wide variety of fluid flow measuring devices have been developed for use in fluid delivery systems in an attempt to accurately determine the volume of the fluid delivered through the delivery system and, more particularly, to the volume of fluid delivered to a particular user of the fluid delivery system. Most natural gas utilities, for example, provide a gas meter at each user location. Such conventional gas meters typically include a diaphragm-type flow sensing apparatus having an accuracy that varies widely as the function of the relative pressure drop across the diaphragm and a number of environmental conditions, such as ambient temperature and relative atmospheric pressure. Such conventional gas meters are typically expensive, bulky, and very difficult to repair and maintain. Moreover, conventional gas and water utility meters require periodic manual reading of the meter in order to determine consumer usage of the fluid over a particular period of time. The manually collected fluid meter information must then be input to a computerized billing system which subsequently issues a bill to the consuming user on a periodic basis.
It can be appreciated that each step in the process of obtaining fluid usage information from a conventional fluid metering device has associated with it inherent inaccuracies due to metering imprecision, changes in mechanical tolerances over the service life of such metering devices, and human-error when reading meter settings and processing meter data. It is well-known in the gas utility community, for example, that such inaccuracies inherent in conventional gas meters can result in overcharging of consumers by as much as two percent above an appropriate billing amount. Considering the vast number of such conventional gas meters currently in service, it can be appreciated that a two percent overcharge occurring each billing cycle over a period of years represents an extremely large surcharge that has traditionally been paid by the consuming public. It is interesting to note that the conventional diaphragm-type gas meter has a design that dates back by more than a century.
A number of electronic metering devices have been developed in an attempt to collect fluid usage data in an automated, efficient manner. U.S. Pat. Nos. 5,126,934, 4,866,633, and 4,839,790, for example, disclose electronic systems for acquiring and interpreting information from a conventional gas meter, determining a flow rate of gas delivered through the conventional gas meter using the acquired information, and then performing various computations and operations using the acquired information. Other gas metering devices, such as those disclosed in U.S. Pat. Nos. 5,369,598 and 4,918,995, for example, employ passive fluid flow sensing apparatuses as improved substitutions for the conventional diaphragm-type gas meters. U.S. Pat. No. 4,940,976, by way of further example, discloses a utility water meter read-out system which purports to acquire water usage information from an existing water meter without requiring any modifications or attachments to the water meter. These and other conventional systems and devices directed to improving the efficiency and convenience of fluid metering suffer from a number of deficiencies resulting from the passive method by which fluid flow rate is typically determined. Such conventional metering devices are referred to herein as passive fluid meters since fluid flow is determined by sensing the fluid as it passes by or through the fluid meter as a sole means for determining fluid flow rate.
It is anticipated that the trend toward deregulation that dramatically impacted the communications industry will very soon affect the quasi-monopolistic gas and water utility industry. De-regulation and privatization of gas and water utilities, for example, will provide an impetus for increased competition for consumer business. Multi-tiered pricing schemes, for example, are currently being used by some utilities to charge users varying rates for gas and water depending on a particular usage. In accordance with such a pricing scheme, essential uses of natural gas, such as for air and water heating, for example, are generally priced at a lower rate than gas used for luxury purposes, such as for heating outdoor pools. Further, it is anticipated that enhanced control over gas and water delivery systems from remote locations will be desirable for providing enhanced service and safety features. It can be appreciated that conventional fluid metering devices and systems cannot be practicably adapted to provide such enhanced functionality, which will certainly be required in a de-regulated competitive utility market.
There exists a need for an improved fluid metering apparatus and method that overcomes the deficiencies inherent in conventional fluid metering schemes. There exists a further need for such a metering system that can provide enhanced safety features currently unavailable when employing fluid metering systems of a conventional design. The present invention fulfills these and other needs.